1. Field of the Invention
This invention relates to handheld electronic instruments and more particularly to instruments for monitoring and diagnosing the operation of a vehicle.
2. Description of the Related Art
The demands placed on an automobile service technician have increased with the increasing complexity of modern vehicles. The systems of vehicles have grown in complexity to reduce pollution and increase safety and comfort. Technicians are required to perform their diagnosis of a vehicle""s system quickly and efficiently, to increase profits of the service station and minimize the amount of time that people""s cars spend in the repair shop. Moreover, while performing these tasks technicians are often require to simultaneously attend to other matters. To meet the needs of the technician serving today""s cars, an increasing array of test equipment has been made available for testing the various systems of cars. The following United States Patents relate to such test equipment.
U.S. Pat. No. 4,298,837 discloses a handheld testing device that functions as a multimeter and has a switch for independently selecting functions and ranges for measuring different electrical quantities.
U.S. Pat. No. 5,367,250 discloses a handheld instrument for performing voltage and continuity tests on electrical systems of vehicles. Red and green LEDs mounted in the housing are operatively interconnected with the probe and power cable through circuitry that causes the red LED to glow when the probe contacts a positive voltage and the green LED to glow when the LED contacts a negative voltage.
U.S. Pat. No. 5,541,840 discloses a system that includes a handheld scan tool that is adapted to interface to the automobile and communicate with various on-board controllers to monitor the operation of the vehicle in real time. While the handheld tool can function as a digital multimeter, it is required to receive information from an on-board controller having a communication bus for communicating with external devices.
U.S. Pat. No. 5,834,935 discloses a digital multimeter with a housing having a battery compartment. A removable battery cover encloses the battery compartment, and has a probe aperture registered with the probe connector, so that a probe may be connected when the battery cover is installed.
None of these patents disclose an handheld electrical instrument that can function as a multimeter and also test various other systems of the vehicle as well. Furthermore, there is no disclosure of an instrument that can change the mode of display screen being used by a simple turn of a rotary switch. Also, the prior art is silent on the combined use of LEDs and a visual display screen to easily, simply and clearly convey information to the technician.
There is thus a particular need for a handheld instrument that is convenient and easy to use for the diagnosing and monitoring the performance of vehicles and that can also function as a multimeter.
The present invention provides an easily controlled handheld electronic instrument for diagnosing operating conditions of a vehicle. One advantage of the present invention is that it is suited for performing the basic functions of a multimeter as well as being able to diagnosis different conditions of a vehicle that a digital multimeter cannot test. This reduces the need for additional equipment that the technician must use and increases the efficiency and profitability of the technician. The instrument has a microprocessor, a memory storage for a computer program controlling the microprocessor and optionally for other information, a display screen, a plurality of buttons, as well as a rotary switch capable of being rotated by one finger of the operator of the instrument. The instrument has at least two display screens selections for monitoring and diagnosing a system of the vehicle, and each display screen has at least one operating mode for monitoring and diagnosing a function of the system, and the display screen selections are capable of being selected by the rotary switch.
Diagnostic and other information related to the operating condition of the test vehicle is conveyed to the operator by the display screen or a combination of the display screen and LEDs. The display screen will change the designation displayed thereon and immediate above the LEDs according to what test is being performed. The LEDs can convey qualitative information such as whether a standard has been met. For example, LEDs may indicate that the battery is low or the alternator should be checked. For each individual display space above the LEDs may indicate a condition of charge or no charge. Other examples are high, medium, medium low, or low; full rich, rich, lean or full lean; or open, good, suspect or bad. Often the qualitative value indicated by a LED is supplemented by a quantitative numerical output on the display screen for the same value.
These together with other various features of novelty which characterize the invention, are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, and the advantages attained by its uses, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated preferred embodiments of the invention.